<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="jquery-1.12.4.min.js"></script>
    <script>
        $(function(){
            var my_div = $('#my-div p')
            console.log(my_div.html());

            my_div.html('麦麦');

            my_div.append('今天天气不错...')
        })
    </script>
</head>
<body>
    <div id="my-div">
        <p>hello</p>
    </div>    
</body>
</html>